1. Field of the Invention
This invention generally relates to a clutch assembly and more specifically to a clutch assembly for use with automotive vehicles and the like.
2. Description of the Prior Art
British Patent Specification No. 1,121,320 discloses a clutch assembly for use with automotive vehicles and the like and comprises a clutch cover secured to a flywheel, an annular pressure plate positioned inside the clutch cover and connected thereto through flexible drive straps and a diaphragm spring positioned outside the clutch cover and pivotally mounted on the clutch cover by mounting means. The diaphragm spring includes an outer annular spring portion engagable with abutments on the pressure plate and a central portion radially inwardly of the mounting means. The mounting means serves as a fulcrum for movement of the diaphragm spring. The diaphragm spring normally urges the pressure plate toward the flywheel so as to engage the clutch. When the driver of the vehicle depresses the clutch pedal the inner portion of the diaphragm spring is moved toward the flywheel by the thrust means operatively connected to the clutch pedal against the resilient force of the diaphragm spring and the outer portion of the diaphragm spring moves away from the pressure plate so as to disengage the clutch. Therefore, it is desirable that the mounting means for the diaphragm spring are positioned radially outwardly as far as possible to reduce the operational force of the clutch pedal. In order to satisfy this desire, the mounting means for the diaphragm spring are generally positioned radially outwardly of the inner periphery of the pressure plate.
It is also desirable that the end of each drive strap to be secured to the pressure plate be positioned radially inwardly of the outer periphery of the pressure plate to reduce the diameter of the clutch. In the case where one end of each drive strap is positioned radially outwardly of the outer periphery of the pressure plate, the pressure plate is provided with a portion to be connected to one end of each drive strap at the outer periphery thereof, thereby causing an increase in the diameter of the clutch. This latter situation is true in the British Patent Specification No. 1,121,320 as well as U.S. Pat. No. 2,770,341.
In a conventional clutch assembly of this type, if the mounting means for the diaphragm spring include pivot rivets and both ends of each drive strap are secured by securing rivets to the pressure plate and the clutch cover respectively, it is impossible to assemble the clutch cover, pressure plate and the diaphragm spring as a unit because the pressure plate connected to the clutch cover obstructs the riveting of the pivot rivets and the diaphragm spring mounted on the clutch cover also obstructs the riveting of one of the securing rivets. Therefore, in order to assemble the clutch cover, pressure plate and the diaphragm spring as a unit, it is necessary to use bolt means which will mount the diaphragm spring on the clutch cover or secure either one end of the drive strap to the pressure plate or the clutch cover. However, the bolt means require a longer time to be attached than rivets and require additional means for preventing the loosening thereof thereby causing poor efficiency in the assembly time of the clutch.
Therefore, in order to obtain greater efficiency in assembly time for the clutch and reduce the production cost of the clutch, it is desirable that the mounting means for mounting the diaphragm spring on the clutch cover include pivot rivets and both ends of the drive straps are secured to the pressure plate and clutch cover by securing rivets.